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Mayb123

Tue Oct 02, 2007 5:01 pm


Laser pointer... ish. help please

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i'm trying to make a 2d sidescroller shooter, and i am trying to make a line appear every time you click the mouse which will (so far) extend from coordinates 0 and 0 all the way across the window intercepting with the mouse cursor. so far i can only make it extend to the cursor. help please. here's the code:

var key : array char of boolean
var reticle : int
var mx, my, button, linebasex, linebasey : int
var reticlenum : string
var weapons :array 1..5 of int
setscreen ("graphics:640;480")
View.Set ("nomouse")
% put "would you like to use reticle one or two?"
% get reticlenum
% if reticlenum = "one" then
%     reticle := Pic.FileNew ("Reticle.bmp")
% elsif reticlenum = "two" then
%     reticle := Pic.FileNew ("Reticle2.bmp")
% end if
loop
    View.Set ("offscreenonly")
    Input.KeyDown (key)
    View.Set ("nomouse")
    Mouse.Where (mx, my, button)



    drawfillbox (0, 0, maxx, maxy, 7)

    % Pic.Draw (reticle, mx - 12, my - 12, picMerge)

    if button = 1 then
        drawline (0, 0, mx, my, 12)
    end if
    delay (1)
    View.Update
    cls
end loop


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CodeMonkey2000

Tue Oct 02, 2007 5:10 pm


RE:Laser pointer... ish. help please

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You can take the angle between the mouse and the player, and use some basic trig to extend the line.


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Mayb123

Tue Oct 02, 2007 5:21 pm


Re: Laser pointer... ish. help please

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and how does one incorporate trig into this?


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CodeMonkey2000

Tue Oct 02, 2007 5:35 pm


RE:Laser pointer... ish. help please

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Tan=opposite/adjacent

opposite=delta Y
adjacent=delta X

tan inverse give you the angle if you have opposite/adjacent


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Clayton

Tue Oct 02, 2007 5:48 pm


RE:Laser pointer... ish. help please

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Why use trig at all? Why not just use your general equation for a line? y = mx + b? You know your y-intercept is going to be zero, and you can figure out slope, and then solve for x.


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CodeMonkey2000

Tue Oct 02, 2007 6:00 pm


RE:Laser pointer... ish. help please

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Or you could do that.
But the advantage with trig is that you can detect obstacles efficiently (ie if there is a ceiling above you, stop the laser).


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Mayb123

Tue Oct 02, 2007 6:34 pm


RE:Laser pointer... ish. help please

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well, my reasoning for this is that i'm going to have a character from which the line will be emitted and that character will be able to run and jump all around the screen (platformer game) and i'm using the mouse as a targeting reticle. so the line will start from the character to the mouse, as i said before


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Mayb123

Tue Oct 02, 2007 6:39 pm


RE:Laser pointer... ish. help please

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oh, and CodeMonkey, thanks for the advice, the only issue is that i don't know where to put that in my code. we were basically given a school project where we have to make a game and learn all the stuff on our own


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CodeMonkey2000

Tue Oct 02, 2007 9:23 pm


RE:Laser pointer... ish. help please

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I think Clayton's method might be better for what you are doing.